Stabilizers for polymers and polymers stabilized thereby

Abstract

New N-alkyl-piperidine derivatives of hydroxy-benzyl-malonic acid are disclosed. These new compounds are useful for stabilizing thermoplastic polymers, in particular polyole fins, against sunlight, heat and oxidation. A process for producing the new compounds is also disclosed, as well as the use thereof as stabilizers of polymers and polymeric compositions.

What we claim is: 
     
       1. N-alkyl-piperidine derivatives of hydroxy-benzyl-malonic acid having the formula: ##STR11## wherein each of R 1 , R 2 , R 3  and R 4 , which may be the same or different, is an alkyl radical having 1 to 6 carbon atoms or R 1  and R 2  together and R 3  and R 4  together form a cycloalkyl radical having 5 to 8 carbon atoms; R 5  is hydrogen, an alkyl radical having 1 to 18 carbon atoms or a 4-hydroxy-benzyl group of the formula: ##STR12##  each of R 6  and R 7 , which may be the same or different, is hydrogen, an alkyl radical having 1 to 6 carbon atoms, an aralkyl radical having 7 to 9 carbon atoms or a cyclo-alkyl radical having 5 to 8 carbon atoms; R 8  is hydrogen or an alkyl radical having 1 to 6 carbon atoms; n is an integer comprised between 1 and 12, and X is oxygen or ##STR13## wherein R 9  is hydrogen, an alkyl radical having 1 to 18 carbon atoms, an alkenyl radical having 3 to 4 carbon atoms, a cyclo-alkyl radical having 4 to 12 carbon atoms, an aryl radical having 6 to 12 carbon atoms or an aralkyl radical having 7 to 9 carbon atoms. 
     
     
       2. N-alkyl-piperidine derivatives of hydroxy-benzyl-malonic acid according to claim 1, in which, in formula (I), each of R 1  R 2 , R 3  and R 4  is methyl; R 5  is butyl or hydroxy-benzyl of general formula: ##STR14## R 6  and R 7  are each tert.butyl, R 8  is hydrogen, X is oxygen and n is an integer from 2 to 6.